1. Field of the Invention
The invention generally relates to network congestion controls, and more particularly, to apparatuses and methods for Access Point Name (APN) based congestion control during a Packet Data Protocol (PDP) context activation procedure.
2. Description of the Related Art
In a typical mobile communication environment, a user equipment (UE), including a mobile telephone (also known as a cellular or cell phone), a laptop computer with wireless communications capability, or a personal digital assistant (PDA) etc., may communicate voice and/or data signals with one or more service networks. The wireless communications between the UE and the service networks may be performed using various wireless technologies, such as the Global System for Mobile communications (GSM) technology, General Packet Radio Service (GPRS) technology, Enhanced Data rates for Global Evolution (EDGE) technology, Wideband Code Division Multiple Access (WCDMA) technology, Code Division Multiple Access 2000 (CDMA-2000) technology, Time Division-Synchronous Code Division Multiple Access (TD-SCDMA) technology, Worldwide Interoperability for Microwave Access (WiMAX) technology, Long Term Evolution (LTE) technology, LTE-Advanced technology, and others.
Take the Long Term Evolution (LTE) technology in compliance with the 3GPP TS 23.060 specification, v10.2.0 (referred to herein as the TS 23.060 specification) and the 3GPP TS 24.008 specification, v10.1.0 (referred to herein as the 24.008 specification) as an example. Before accessing a service, the UE has to perform a PDP context activation procedure to activate a default PDP context to the Serving GPRS Support Node (SGSN) and a specific Gateway GPRS Support Node (GGSN), which can support the service. To begin the PDP context activation procedure, the UE transmits an ACTIVATE PDP CONTEXT REQUEST message to the service network to request for the activation of a default PDP context for the service. As shown in FIG. 1, if the service network decides to accept the request, it replies to the UE with an ACTIVATE PDP CONTEXT ACCEPT message which comprises the configurations for activating the PDP context, and the PDP context activation procedure ends successfully. Otherwise, as shown in FIG. 2, if congestion occurs in the APN associated with the requested PDP context, the service network replies to the UE with an ACTIVATE PDP CONTEXT REJECT message which comprises a rejection cause with a cause value #26 (indicating insufficient resources) and a value of a back-off timer. When receiving the ACTIVATE PDP CONTEXT REJECT message, the UE starts the back-off timer with the received value and does not initiate any subsequent activation of the PDP context for the rejected APN until the back-off timer expires or the subscriber identity card coupled to/in the UE is replaced or removed.